Keylock for electrical plugs



R. M. LAFF KEYLOCKFOIR ELECTRICAL PLUGS Filed July 22, 1968 INVENTOR.EMWci'fQ/fi BY Baa/471.1,

United States Patent O 3,524,029 KEYLOCK FOR ELECTRICAL PLUGS Robert M.Latf, 2844 W. Gregory St., Chicago, Ill. 60625 Filed July 22, 1968, Ser.No. 746,603 Int. Cl. H01h 9/28; H01r 13/70 US. Cl. 200-44 6 ClaimsABSTRACT OF THE DISCLOSURE A locking device comprising a housing havinga compartment for enclosing an electrical plug, such as an applianceplug. A socket is mounted in the housing adjacent the compartment and isconnected to a line cord which in turn is connected to a conventionalelectrical power source. The socket is adapted to receive the electricalplug. A key-actuated switch is mounted in the housing and interposedbetween the socket and power source for opening or closing theelectrical circuit. The device is provided with means for permanentlysealing the electrical plug within the housing compartment after theplug is inserted into the socket.

BACKGROUND OF THE INVENTION This invention relates generally toelectrical connectors and circuit breakers with unauthorized-usepreventing means. In particular, this invention pertains to a lockingdevice for use with electrical appliance plug to prevent theunauthorized use of the appliances.

The closest prior art includes many devices for preventing theunauthorized use of appliances. These devices fall generally into twogroups: 1) keylock receptacles for appliance cord plugs; and (2) plugswhich contain key-operated disabling means. The devices of the firstgroup have the disadvantage of being too cumbersome to use becausewhenever the appliance is to be operated, the plug must be removed fromthe receptacle and inserted into an electrical outlet. The second groupof articles have the disadvantage of having to be substituted for theconventional plug normally found on the appliance, by either themanufacturer or the consumer of the appliance.

Therefore, an object of this invention is to provide a locking devicewhich can be permanently connected to existing electrical plugs andwhich is easy to install and operate. A further object of this inventionis to provide a locking device which can be economically manufacturedand sold to the consuming public at a relatively low price. Additionalobjects of this invention will become manifest from the description,drawings, and claims.

SUMMARY OF THE INVENTION The device of this invention includes a housingcontaining a compartment for retaining a conventional electricalappliance plug and a socket mounted in the housing adjacent thecompartment. The socket is electrically connected to a line cord whichterminates in a conventional plug, and a key-actuated switch isinterposed in the line between the socket and the cord. The switch ismounted in the housing with the keyhole being externally accessible. Theappliance plug is inserted into the socket and is enclosed within thecompartment provided for it. A cover is permanently secured to thecompartment by drive screws or like means so that the appliance plugcannot be removed without destroying the locking device. When the deviceis connected to a nappliance, the applitime can be controlled by thekey-operated switch so that the appliance can be secured againstunauthorized use.

3,524,029 Patented Aug. 11, 1970 "ice BRIEF DESCRIPTION OF THE DRAWINGSDESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, an appliancelocking device 10 of this invention is shown. Thisdevice includes a housing 12 having a compartment 14 for holding aconventional appliance plug, such as the threepronged plug 16 shown inFIG. 3. The housing 12 is preferably constructed of plastic or othersuitable non-conductive material. The plug 16 is inserted into a socket18 which is retained by a mounting plate 20. The cord 17 of theappliance is guided about a post 19 (see FIG. 3) and through an opening21 in the housing 12. While a three-hole grounded type socket 18 andthree-prong grounded type plugs 16 and 24 are shown, a two-holeungrounded receptacle and ungrounded two-prong plugs may be employed foruse with conventional two-pronged electrical plugs. In the lattersystem, two wire connections would be employed so that the groundconnection 28 would be eliminated.

Referring to FIG. 3, it will be seen that the socket 18 is electricallyconnected to a line cord 22 which terminates in a plug 24. The socket 18is connected to the line 22 by wire 26 and wire nut 30. A ground wire28, shown in dotted lines in FIG. 3, extends between the socket 18 andthe line 22, wire 28 being connected to the line 22 by a wire nut 32,also shown in dotted lines in FIG. 3.

Interposed between the socket and the line 22 is a switch 34. The switchis electrically connected to the socket at terminal 35 by wire 36 and isconnected to the line 22 at terminal 38. The line cord 22 extends fromthe switch 34 about a post 37, through guides 39, into the compartment14, and out of an opening 40 in the housing 12. The switch is actuatedby a removable key 42, which is movable between open and closedpositions. The switch is mounted within the housing 12 and the keyhole ais externally accessible. While any suitable key-operated switch may beemployed in this invention, I have found that a 15 amp., to 277 voltA.C. single pole, lock-type switch manufactured by Pass and Seymour,Inc., Catalog No. ACDl1-L, gives satisfactory performance.

In FIG. 1 a cover 44 is shown for the compartment 14. After theappliance cord is connected to the socket 18, the cover 44 is placed onthe ledges 45 provided therefor and is permanently fastened to thehousing 12 by drive screws 46 and 48 or other suitable means. The drivescrews 46 and 48 are inserted through openings 50 and 52 in the cover 44and into holes 54 and 56 provided in the housing 12. The screws aretapped into place (as shown in FIG. 2) by a hammer or other suitablemeans, and once inserted cannot be removed without destroying thedevice. Only two screws are necessary in the illustrated embodimentbecause one end 58 of the cover is inserted under an overhanging portion60 (FIG. 2) of the top of the portion of the housing adjacent thecompartment 14.

Although drive screws are specifically disclosed, other suitablepermanent fastening means may be employed. Also, the cover may beconnected to the housing in other convenient ways than the one describedhereinbefore.

While a specific embodiment of this invention has been described above,it should be understood that the invention is not limited thereto sincemany modifications may be made; and it is contemplated, therefore, tocover by 3 the following claims any such modifications as fall withinthe true spirit and scope of this invention.

What is claimed is:

1. A locking device for an electrical plug comprising:

(1) a housing;

(2) a compartment in said housing for enclosing said elcetrical plug,said compartment having an opening in one side to insert said plug;

(3) a socket in said housing adjacent said compartment adapted toreceive said electrical plug;

(4) means disposed in said housing for supporting said socket;

(5) an electric line cord connected to said socket, said cord extendingout of said housing through an opening therein and terminating in a plugwhich is adapted to be inserted into a conventional electrical outlet;

(6) a key-actuated switch in said line intermediate said socket and saidline cord plug, said switch being movable between open and closedpositions and being mounted in said housing with the keyhole externallyaccessible;

(7) means for electrically connecting said socket with said switch sothat when said switch is open said socket will be disabled;

(8) means for permanently sealing said electrical plug within saidhousing, said means including a cover which fits over the opening insaid compartment for said appliance plug and at least one fasteningmeans which is adapted to permanently fasten said cover to said housing.

2. The apparatus of claim 1 wherein the housing has a top portion whichextends part way across the top; the means for supporting said socket isa wall located intermediate the ends of said housing and under saidhousing top portion so that a part of said housing top portion overhangssaid wall, said wall supporting said socket so that the apertures insaid socket for receiving the appliance plug face the plug enclosingcompartment; and the cover which fits over the opening in saidcompartment has one end which extends under the overhanging part of saidhousing top portion and has an aperture adjacent the opposite endthereof, said housing having an aperture which corresponds to theaperture in said cover,

both of said apertures being adapted to receive said permanent fasteningmeans.

3. The apparatus of claim 2 wherein said housing and said compartmentcover each have a plurality of corresponding apertures which are adaptedto receive a plurality of fastening means.

4. The apparatus of claim 3 wherein said housing and said compartmentcover each have two corresponding apertures which are adapted to receivethe fastening means and said fastening means comprises two drive screws.

5. The apparatus of claim 1 wherein the wall located in the housingdescribes a second compartment in said housing, said second compartmentcontaining said keyactuated switch and the means for electricallyconnecting said socket to said switch, said second compartment alsocontaining that part of said electric line cord which is connected tosaid socket.

6. The apparatus of claim 5 wherein the wall has an opening throughwhich the electric line cord passes into the plug enclosing compartment,said line cord passing out of said plug enclosing compartment throughsaid opening in said housing for said line cord.

References Cited UNITED STATES PATENTS 1,588,984 6/1926 Nutting 200-44 X1,656,586 I/ 1928 Hemingway ZOO-44 2,643,787 6/1953 Rockman.

2,654,073 9/ 1953 Katz.

2,733,416 1/1956 Bualt.

2,759,159 8/ 1956 Teetor.

2,761,028 8/ -6 Teetor.

2,879,494 3/ 1959 Teetor.

2,955,272 10/ 1960 Gallaudo.

3,345,603 10/ 1967 Cohen.

ROBERT K. SCHAEFER, Primary Examiner H. J. HOHAUSER, Assistant ExaminerUS. Cl. X.R. 200-51; 307--114

